Analog multiplier with ratio indicating means



June 6, 1967 L. J. CHU 3,324,283

ANALOG MULTIPLIER WITH RATIO INDICATING MEANS Filed May 1 1963 3 Sheets-Sheet l AND/OR INDICATOR SYNCHRONIZER L- STORAGE LAN JEN CHU INVENTOR.

BY Mwm ATTORNEYS June 6, 1967 L. J. cI-Iu 3,324,283

ANALOG MULTIPLIER WITH RATIO INDICATING MEANS Filed May 1, 1963 3 Sheets-Sheet 2 SIGNAL AT DIRECTION AND SPEED I I TAG SIGNALS INFORMATION TAG SIGNALS ./P, P2 L/V L/V L 3/ L/V TIME FIG. 3B

' GI 62 45 /s p A L l5- BIT CLOCK i G3 46 couNTE R 43 I 66 SIGNALS SCHMITT o I o GI9 TRIGGER FFI CIRCUIT (couPLEuEnT 5) l4-B|T COUNTER END CARRY V STROBE OR 5| 54 TIMING PULSE RESET/c 54 TELETYPE /55 BUFFER FIG. 3A

LAN JEN CHU INVENTOR.

BY and ATTORNEYS June 6, 1967 I L. J. CHU 3,324,283

ANALOG MULTIPLIER WITH RATIO INDICATING MEANS Filed May 1, 1963 3 Sheets-Sheet 5 SIG ALS TRIGGER CIRCUIT Z V O m m N ,2 0 LAN JEN CHU INVENTOR.

'1 o 0 (D 3 E ATTORNEYS United States Patent 3,324,283 ANALOG MULTIPLIER WITH RATIO INDICATING MEANS Lan .1. Chill, R0. Box 387, Littleton, Mass. 01460 Filed May 1, 1963, Ser. No. 277,387 13 Claims. (Cl. 235-6111) ABSTRACT OF THE DISCLOSURE The invention relates to an electromagnetic-wave reflecting system for code-identification of moving vehicles or the like, embodying different-plane reflector surfaces.

The present invention relates to methods of and systems for radiant-energy identification; and, more particularly, to detecting coded electromagnetic-wave reflectors associated with such apparatus as railroad cars and the like.

It has heretofore been proposed to identify and keep track of such vehicles as railroad cars and the like by using electromagnetic energy, such as microwaves or infrared waves, to illuminate identifying reflecting coded tags mounted thereupon. Unfortunately, however, such proposals have been subject to deleterious changes in the tagreflecting surfaces caused by dirt, grease and other contaminants; microwave-slot radiators becoming filled, or infra-red absorbing layers having their surfaces modified. In addition, ambiguities in signal-reflected information resulting from surface and other positional changes, and lack of sharp relative signal levels, such as no-signal (zero) and finite signal conditions, render these proposals inaccurate and thus unsatisfactory.

An object of the present invention, accordingly, is to provide a new and improved method and system of the character described that shall not be subject to the abovementioned disadvantages, but that, to the contrary, shall not be affected by surface contamination or similar changes, being dependent substantially exclusively upon optical geometry.

Still another object is to provide a new-and-improved binary-signal railroad or other similar reflected-energy identification system.

Another object is to provide a novel identification reflector.

Other and further objects will be explained hereinafter and will be more particularly pointed out in connection with the appended claims. In summary, however, the invention contemplates, in a preferred embodiment, an electromagnetic system having, in combination, electromagnetic-wave reflecting apparatus comprising at least a pair of substantially planar reflectors the planes of which intersect a common plane, at substantially plus and minus similar angles, preferably of the order of thirty degrees, and a pair of electromagnetic-wave detectors respectively disposed along directions substantially tangent to the pair of reflector planes Preferred constructional details are hereinafter set forth.

The invention will now be described in connection with the accompanying drawing, FIG. 1 of which is a combined perspective view and schematic circuit diagram of apparatus constructed in accordance with a preferred embodiment thereof;

FIG. 2 is a partial isometric view of a modified reflector or tag;

FIG. 3 is a view similar to FIG. 1 of a modification particularly adapted for pulsed-wave energy;

FIG. 3A is a block schematic diagram of a preferred circuit for providing timing, counting and signal-identifyin g functions in the system of FIG. 3; and

3 ,324,283 Patented June 6, 1967 "ice FIG. 3B is a timing wave-form of the system of FIGS. 3 and 3A.

Referring to FIG. 1, the underside of a railroad car or the like, generally indicated at 2, traveling in the direction of the arrow A, is shown provided with an identifying tag in the form of an array of electromagnetic-wave reflectors 4 comprising differently oriented successive laterally displaced substantially planar reflectors 6, 8, 10, 14, 16, etc., prearranged in a predetermined code that is to identify the particular car 2. As an example, the reflectors of the tag 4 may represent bits of a binary-coded character, such as the code 11110, representing a first letter or numeral in the identification tag; with the reflectors 16, 14, 10 and 8 illustratively shown similarly oriented at an acute angle +0 to the plane of the tag background at the right-hand edge of the tag 4 to represent the digit 1, and the reflector 6 shown oriented at the acute angle 6 to the tag plane at the left-hand tag edge to represent the digit 0. In actual practice, as many as fifty or more reflector units may be employed to permit identification of the car and other particles relating to the same.

Electromagnetic energy of, for example, the infra-red spectrum, may be converged at 1 upon the tag 4, being reflected by the reflector units oriented in the manner of the reflector 6, at T toward a detector station II; and, by reflector units oriented in the manner of the reflectors 8, 10, 14 and 16, along T toward a detector station I. In accordance with a useful feature of the present invention, the optical geometry and arrangement of the system may be critically adjusted to insure that detector station 1 receives a finite signal from reflector units oriented in the manner of units 8, 10, 14 and 16, in the illustrated example, but zero signal from units oriented in the manner of the reflector unit 6. This condition must obtain, moreover, whether there is specular reflection from mirror-like reflector surfaces or whether dirt or other interfering contaminants or obstructions have rendered the reflection diffuse.

It has been discovered, both theoretically and experimentally, that at substantially one acute angle 0 a perfect no-signal or zero condition can be obtained, irrespective of specular or diffuse reflection and thus independently of the surface condition of the tag. If the detector stations I and II are optically alined to receive radiation substantially exclusively along directions T and T respectively tangent to the plane of reflector units oriented in the manner of the unit 6 (-0) and to the plane of reflector units oriented in the manner of each of the units 8, 10, 14, 16 (+0), and the angle 9 is adjusted to substantially 30 degrees, then detector stations I and II will receive absolute zero signal from respective tangentially oriented reflectors 6 and 8, 10, 14, 16, respectively. Some finite signal, the level of which depends on the intensity of the illuminating radiation I and the surface condition of the reflector units, however, will be received from the nontangentially oriented unitsproviding a positive distinction between no signal and some signal. Variations from the strict substantially 30-degree orientation can be employed, particularly for diffuse reflection, though optimum performance is attainable at or near that orientation.

A source of electromagnetic radiation is shown at 18 in the illustrative form of a flash-tube having a light output preferably containing substantial infra red energy. The flash lamp 18 is flashed by a conventional trigger circuit 26 (though continuous-wave operation may be employed) and may, for example, be positioned somewhat centrally between the rails R R The radiation from the source 18 is focused, as by a lens 18', upon a central region of the tag 4 being carried on the undercarriage of the railroad car 2, a constant predetermined height above the track; the tag 4 extending, for example, either longitudinally along the car or transversely thereof, or parallel to an axle, as illustration. The detector stations I and II may be mounted between or outside the rails R R along the appropriate critical directions T and T having respective radiation-to-electric energy transducers 2t) and 20, preferably of the photo-actuated on-off switching type, that switch on only upon reception of a threshold value of received radiation. Other types of detectors and transducers may obviously also be employed. Adjustment to insure the respective tangential directions of reception T T may be effected by lenses 22-22 and limiting apertures 2424', as is Well known.

In experimental tests, using a flashing lamp of the type described in US. Letters Patent No. 2,977,508 issued to K. J. Germeshausen and marketed by Edgerton, Germeshausen & Grier, Inc. as the FX6A, having 50 milliwatt-seconds per flash, triggered by the flash circuit 26 at repetition rates from 10 to 200 cycles per second, distances of from 14 inches to 4 feet between light source 18 and reflecting surface 4 were employed, with the light focused upon the reflecting surface 4, as shown in FIG. 1. Photoactuated receiving detectors 20, 20', of the General Electric type ZI235A were alined along the respective tangential directions T and T being positioned at a distance of from 22 /2 inches up to about 6 feet from the reflector tag 4, and with the detectors being switched by signals detected from the non-tangentially alined reflector units even though covered with various degrees of surface coatings and contamination ranging from uncontaminated specular surfaces to pitch black layers, thus showing independence of surface condition.

No triggering of the detectors at all was produced along the tangential direction, providing a sharp and consistent zero signal. This was found, in actual practice, to be true for a range of a few degrees from the strict tangential conditionthe latitude depending upon the adjusted sensitivity of the switching detectors 20, 20'.

Referring to the detecting, monitoring or receiving station I, as the units 16, 14, 10, 8, 6, etc. are successively carried or moved past the station by the moving railroad or other car 2, the detector 20 will be switched on for pulsed radiation signals received from units 16, 14, 10 and 8, but switched off when reflector unit 6 passes by. Assuming that there is synchronization, later explained, between speed of movement of the car 2 and the flashing or pulsing of the flash lamp 18, as from a synchronization or timing source 30 that responds to the speed of the car 2 and triggers the flash-trigger circuit 26, as hereinafter described, to produce a flash for each reflector unit or bit that passes by, the received signals may be amplified at 28 and applied by conductors 3 to a storage or indicator or recorder system 32, such as a teleprinter, that may convert the signals to predetermined identification characters. If desired, the complementary output of the detector 20' at station II may be employed to check the accuracy of the signals, as by feeding the same at 3 to a gate 32' that will prevent signal-application to the system 32 if the outputs of the amplifiers 28 and 28', respectively associated with the detectors 20 and 20', are not complementary.

Other orientations of the acute angle reflector tags may also be employed, as in the lateral array 4' of FIG. 2, and the tags may clearly be positioned in other locations than the railroad undercarriage, including the side of the car for monitoring from track-side stations I and/ or II upon side-illumination from the radiation transmitter 18.

In all cases, the passage of railroad cars 2 or similar vehicles past predetermined identification stations of this character will provide an automatic recording of the identified cars, enabling the monitoring of their location without the present-day necessity for operators attempting visually to read and record numbers.

It remains, now, to explain the details of flash synchronization with car speed and of other constructional matters previously mentioned. In the embodiments of FIGS. 3 and 3A, which are to be considered as one system, this synchronization is initiated when the wheel 34 of the vehicle passes over a predetermined section of track R at which magnetic-field-coupled excitation and sensor coils 36 and 37 are inserted; the former energized from an excitation source 35, and the latter feeding an initiating impulse to an amplifier 38, upon passage of the wheel 34 over the section containing coils 36 and 37, near the region of the transmitter lamps 18. The trigger circuit 26 for flashing a plurality of lamps 18, corresponding to a plurality of tag reflector units, may then be energized. It is still necessary, however, to insure that lamps 18 flash at the correct rate, corresponding to the speed of the train or other vehicle in order to effect strobe or pulse illumination of each reflector unit as it passes by. To this end, a direction-and-speed identifying tag portion (so-labelled in FIG. 3) is provided in advance of the identification tags 4", shown of the same code signal as in FIG. 1. The tag reflector units of FIG. 3 will be of the type shown in FIG. 1 or 2, though, for purposes of convenience, they are shown diagrammatically as flat units in FIG. 3, bearing, however, the 0 or 1 identifying reference to indicate that, in actual practice, they are oriented at :0, as before described.

In accordance with this technique, the direction-andspeed portion of the tag is shown comprising alternate 1 and 0 reflector units; but the last 0 unit is Wider by fifty percent than the other reflector units, as indicated by 3/ 2L in FIG. 3. The time unit T during which the successive flash lamps or other radiation sources 18 are to be pulse-operated so as to enable synchronization of the illuminating with the passage of each reflector unit, will, as before described, depend upon the velocity of the car 2. Thus, in the timing diagram of FIG. 3B, the time unit T for the first 1, 0 and 1 units of the directionand-speed-determining portion of the tag will be L/ V, where V is the car velocity; whereas the last 0 unit will be 3/2 L/V. At a maximum speed of 60 miles per hour, and a tag unit width of one inch, the maximum time unit required will be 1 millisecond. In order to accommodate, say fifty one-inch reflector units in an identifying tag, therefore, a reference or clock pulse-generator frequency for the system is selected at 1 megacycle in the circuit of FIG. 3A, later to be described.

Information on direction and speed will be obtained from the direction-and-speed-deterrnining reflector units, insuring synchronization with car velocity for proper flash-illuminating of the identifying reflector units of the tag 4. The manner in which this is effected will now be explained in detail with reference to FIG. 3A. Briefly, however, the concept involves producing in a counter A, in response to receipt of a signal from the first 1 reflector unit of the direction-and-speed-determining tag portion, a count of impulses, from a clock pulse generator 42, that is proportional to 2T. Flip-flops in the circuit of FIG. 3A will change state on the trailing edge of the first applied pulse P FIG. 3B, and, following the trailing edge of the second pulse P FIG. 3B, that count, divided by 2 (to give the time interval T as determined by the car velocity V) is transferred to a count register B. In register B the count is reduced to zero, producing an end carry that causes the count in A (divided by 2) to be transferred to count register B, which is again reduced to zero. This process produces an end carry pulse every T units of time, which are used for strobe or timing synchronizing illumination pulses to gate further received signals from the car-identifying tag reflector units 4".

The photocells or similar detectors, such as the set I of FIG. 3, either receive a signal or not from a tangentially oriented reflector unit 0 or a non-tangential unit 1. The photocell output is applied through a Schmitt trigger circuit 40, FIG. 3A, for squaring-up the signal impulse, and by Way of conductor 41, to a first flip-flop circuit indicated at FF1 that is normally in the 0 state.

The first input signal from the trigger circuit 40 sets FFI to the 1 state. At the leading edge of the first pulse preceding the identifying tag portion 4", FFl is set to the "1 state, therefore, and by way of output conductor 43, opens a gate G1 on the trailing edge of that first pulse. A further gate G2 is maintained open at this time since a further flip-flop stage FFZ, feeding the same at 44, is in the 0 state. An impulse from a timing clock 42, such as a one-megacycle pulse generator, may, therefore, pass through gates G1 and G2 and, by conductor 45, into a pulse counter A, such as a -bit counter of conventional form.

When the first flip-flop stage FFI is complemented to the 1 state, its output is fed at 43 through gate G3 and conductor 46 to stage FFZ. Flip-flop stage FF2 will then complement on the trailing edge of the second pulse, to the 1 state, opening gate G2 and interrupting the clock pulses that are being fed from the clock 42 into the counter A. From the time of the falling edge of the first pulse to the falling edge of the second pulse, therefore, the counter A counts impulses which are inversely related to the speed of the car and thus are enabled to serve as controlling devices for insuring the successive flashing of the successive flash lamps 18 at the proper rate to illuminate the successive reflector units as they pass by the detecting region I.

Flip-flop stages FF]. and FF2 are now both in the 1 state. The next clock pulse, therefore, will pass through gates G1, and, by conductor 47, through a further gate G4, and along conductor 48, to reset flip-flop stage FFI to the zero state. This will also serve to transfer the 15- bit count stored in counter A, by the opening of the or gate G5, by means of and gates G6 through G19, to a fourteen-bit counter B, transferring the fourteen most significant binary digits from counter A into counter B in a complemented manner and thus, in effect, dividing by two. The selection of the most significant binary digits effects this division by two.

Flip-flop FFI is also reset to the 0 state, opening gate G20 by the output at 49 and allowing clock pulses to pass from the pulse-generator clock 42 through gate G20 and a further gate G21 and by way of conductor 59 to add increments to counter B. Counter B is thus incremented until an end carry is produced that serves as the strobe or timing pulse at 51 for flashing the flash lamps. This end carry pulse is also transmitted by way of conductor 52 and gate G5 to transfer the count contents of counter A to counter B, again, for repetitive processes. The end carry pulse also feeds counter C at 53. At the end of 51 counts, representing the maximum number of reflector units-to-be-identified in a car tag, in this example, counter C will reset the clock-feed-controlling flip-flop FFZ, along conductor 54, interrupting the whole cycle and readying the apparatus for similar operation upon the advent of the next car 2 with its tag that is to be identified.

A further flip-flop stage FF3 is also connected at 51 to the end carry output 51 of counter B in order that, after the first output which occurs between the second velocity identifying pulse and the actual identification tag portion 4", F1 3 will be enable to remain open for the next 50 identifying tag-unit counts. F1 3 is also reset, as is FFZ, by conductor 54', at the end of the 51 counts of the counter C.

The output of flip-flop stage F1 3 is fed through and gates G22 and 23 to enable the signal from the photocell or other reflection detectors 20 at station 1, FIG. 3, representing either digital zeros or ones, to be fed, for example, to a teletype or other digital informationdevice buffer stage 55, thus to store or indicate the next 50 reflector-unit reflection signals from the tag 4" that identifies the car 2.

Proper direction indication of the car 2 may be effected by having two identical tags that are constructed in reverse senses, with information transferred to teletype upon receipt of the unique first two pulses before-dcscribed. An unambiguous tag may also be provided for determining the proper direction so that the teletype receives only the information following the same. The geometrical optical features of the invention, moreover, are not restricted to electromagnetic radiation of light wavelengths, visible and invisible. Further modifications will also occur to those skilled in the art and all such are considered to fall within the spirit and scope of the invention as defined in the appended claims.

What is claimed is:

1. An electromagnetic system having, in combination, electromagnetic-wave reflecting apparatus comprising at least a pair of laterally displaced substantially planar reflectors the planes of which intersect a further common plane at substantially plus and minus the same angle, respectively, means for transmitting electromagnetic waves toward the said reflecting apparatus, and a pair of electromagnetic-wave detectors respectively disposed along directions substantially tangent to the said planes of the pair of reflectors, the wave-transmitting means producing pulses of electromagnetic waves, and there being further provided means for moving the reflecting apparatus past the said detectors and means for synchronizing the pulses of electromagnetic waves with the said moving to insure the transmission of a pulse of waves to each reflector.

2. An electromagnetic system having, in combination, electromagnetic-wave reflecting apparatus comprising a plurality of substantially planar reflectors oriented to provide a binary code, with the planes of at least a pair of the reflectors intersecting a further common plane at plus and minus substantially the same angle, respectively, means for transmitting electromagnetic waves to the reflectors for reflection therefrom, an electromagnetic-wave detector disposed along a direction substantially tangent to the plane of one of the said air of reflectors so as to detect none of the waves reflected therefrom to provide a 0 indication, the detector receiving waves diifusely and specularly reflected from the other reflector of the pair to provide a 1 indication, and binary-indicating means connected to the detector to indicate the said hinary code, the reflecting apparatus being moved past the detector and there being provided means for determining the velocity of such movement and means for controlling the transmitting of the electromagnetic waves in accordance with the said velocity.

3. An electromagnetic system as claimed in claim 2 and in which there is provided means for determining the velocity of such movement for controlling the transmitting-controlling means in accordance with the said ve locity to effect synchronization of the pulses of electromagnetic waves with movement of the apparatus, thereby to insure the transmission of at least a pulse of waves to each reflector.

4. An electromagnetic system as claimed in claim 3 and in which the reflector apparatus is provided with velocity-determining reflectors.

5. An electromagnetic system as claimed in claim 4 and in which counter and pulse clock means are provided, responsive to signals received from the velocity-determining reflectors for determining the time elapsed between predetermined of the velocity-determining reflectors, thereby to provide a measure of the said velocity.

6. An electromagnetic system as claimed in claim 5 and in which the counter means comprises a first flip-flopcontrolled counter connected to receive clock pulses from the clock means to produce a count proportional to twice the time unit T between predetermined velocity-determining reflectors that have moved past the said transmitting means, and a second counter connected to receive the transfer of the said count divided by two and adapted to have its stored count reduced to zero to produce an end carry pulse every T units of time, and means for applying the end carry pulse to trigger the transmitting means.

7. An electromagnetic system as claimed in claim 6 and in which means is provided for producing an initiating impulse upon the arrival of the reflector apparatus at the region of the transmitting means.

8. An electromagnetic system as claimed in claim 7 and in which the initiating-impulse-producing means comprises a sensor for detecting the presence of a vehicle carrying the reflector apparatus.

9. In a reflected-wave identifying system, a plurality of reflector units carried by an object, means for trans mitting pulses of radiation for reflection from the units as they move by a predetermined region, means for determining the velocity of such movement, and means for synchronizing the transmitting of the pulses of radiation in accordance with such velocity determination to insure the transmission of at least a pulse of radiation for each of a group of the reflector units, the plurality of reflectors comprising a group of one of velocityand directiondetermining units and a coded group of identification reflector units.

10. Apparatus as claimed in claim 9 and in which counter and pulse clock means is provided, responsive to signals received from the group of velocity-determining reflector units for determining the time elapsed between predetermined of the velocity-determining reflector units, thereby to provide a measure of the said velocity.

11. An electromagnetic system as claimed in claim 10 and in which the counter means comprises a first flip-flopcontrolled counter connected to receive clock pulses from the clock means to produce a count proportional to twice the time unit T between predetermined velocitydetermining reflectors that have moved past the said transmitting means, and a second counter connected to receive the transfer of the said count divided by two and adapted to have its stored count reduced to zero to produce an end carry pulse every T units of time, and means for applying the end carry pulse to trigger the transmitting means.

12. An electromagnetic system as claimed in claim 9 and in which means is provided for producing an initiating impulse upon the arival of the reflector apparatus at the region of the transmitting means.

13. An electromagnetic system as claimed in claim 12 and in Which the initiating-impulse-producing means comprises a sensor for detecting the presence of a vehicle carrying the reflector apparatus.

References Cited UNITED STATES PATENTS 1,966,354 7/1934 NOX0n 178-3 2,853,158 9/1958 Brandon et a1 18748 2,956,117 10/1960 Ernst et a1. 1786.8 3,180,996 4/1965 De Good et al. 250-223 DARYL W. COOK, Acting Primary Examiner.

MAYNARD R. WILBUR, Examiner.

A. L. NEWMAN, Assistant Examiner. 

1. AN ELECTROMAGNETIC SYSTEM HAVING, IN COMBINATION, ELECTROMAGNETIC-WAVE REFLECTING APPARATUS COMPRISING AT LEAST A PAIR OF LATERALLY DISPLACED SUBSTANTIALLY PLANAR REFLECTORS THE PLANES OF WHICH INTERSECT A FURTHER COMMON PLANE AT SUBSTANTIALLY PLUS AND MINUS THE SAME ANGLE, RESPECTIVELY, MEANS FOR TRANSMITTING ELECTROMAGNETIC WAVES TOWARD THE SAID REFLECTING APPARATUS, AND A PAIR OF ELECTROMAGNETIC-WAVE DETECTORS RESPECTIVELY DISPOSED ALONG DIRECTIONS SUBSTANTIALLY TANGENT TO THE SAID PLANES OF THE PAIR OF REFLECTORS, THE WAVE-TRANSMITTING MEANS PRODUCING PULSES OF ELECTROMAGNETIC WAVES, AND THERE BEING FURTHER PROVIDED MEANS FOR MOVING THE REFLECTING APPARATUS PAST THE SAID DETECTORS AND MEANS FOR SYNCHRONIZING THE PULSES OF ELECTROMAGNETIC WAVES WITH THE SAID MOVING TO INSURE THE TRANSMISSION OF A PULSE OF WAVES TO EACH REFLECTOR. 